vhost: check owner before we overwrite ubuf_info

If device has an owner, we shouldn't touch ubuf_info
since it might be in use.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index beee7f5787e6..60aa5ad09a2f 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -344,13 +344,19 @@ static int vhost_attach_cgroups(struct vhost_dev *dev)
 }
 
 /* Caller should have device mutex */
+bool vhost_dev_has_owner(struct vhost_dev *dev)
+{
+        return dev->mm;
+}
+
+/* Caller should have device mutex */
 long vhost_dev_set_owner(struct vhost_dev *dev)
 {
         struct task_struct *worker;
         int err;
 
         /* Is there an owner already? */
-        if (dev->mm) {
+        if (vhost_dev_has_owner(dev)) {
                 err = -EBUSY;
                 goto err_mm;
         }